ScalaMock: Mocking a Trait with initializations via lazy val

Question

I've the following trait which I want to mock:

trait TraitA extends TraitB {
   private lazy val internalObject = new ServiceA()
   internalObject.setSomeVal("someVal")
   internalObject.setSomeOtherval("someOtherVal")
   private lazy val anotherObject = new ServiceB()

   def functionA(paramA: typeB): typeC = {
       // some code using internalObject & anotherObject
   } 
}

When using ScalaMock, I try to do

val mockTraitA = mock[TraitA]

it fails with java.lang.NullPointerException as probably it is not able to initialize the mock version of this trait properly due to the presence of private lazy val's ?

What could be the correct way to initialize such a trait?

score 1 · Answer 1 · answered Nov 04 '17 at 17:57

For mockTraitA, the line internalObject.setSomeVal... will be executed when the constructor for the trait runs. There's no way to prevent that unfortunately.

If you can, try to refactor to this:

private lazy val internalObject = {
  val t = new ServiceA
  t.setSomeVal("someVal")
  t.setSomeOtherval("someOtherVal")
  t
}

ScalaMock: Mocking a Trait with initializations via lazy val

1 Answers1